Metal‐Based Nanomaterials in Biomedical Applications: Antimicrobial Activity and Cytotoxicity Aspects

Targeted delivery of compounds to particular cell subsets can enhance therapeutic index by concentrating their action on the cells of interest. Because attempts to target tumors directly have yielded limited benefit, we instead target endogenous immune cell subsets in the circulation that can migrate actively into tumors. We describe antibody-targeted nanoparticles that bind to CD8+ T cells in the blood, lymphoid tissues, and tumors of mice. PD-1+ T cells are successfully targeted in the circulation and tumor. The delivery of an inhibitor of TGFβ signaling to PD-1-expressing cells extends the survival of tumor-bearing mice, whereas free drugs have no effect at such doses. This modular platform also enables PD-1-targeted delivery of a TLR7/8 agonist to the tumor microenvironment, increasing the proportion of tumor-infiltrating CD8+ T cells and sensitizing tumors to subsequent anti-PD-1. Targeted delivery of immunotherapy to defined subsets of endogenous leukocytes may be superior to administration of free drugs.Targeted delivery of immunomodulatory compounds to defined subsets of endogenous immune cells may improve the efficacy of combination immunotherapies. Here, the authors use PD-1-targeting nanoparticles containing a TGFβ inhibitor or a TLR7/8 agonist to deliver these payloads to T cells or via T cells to the tumor microenvironment, respectively, leading to anti-tumor efficacy in vivo.

T cell-targeting nanoparticles focus delivery of immunotherapy to improve antitumor immunity

Nanotechnology is the branch of science which deals with particles ranging between 1–100 nm. These particles are called nanoparticles, and they exhibit unique electronic, optical, magnetic, and mechanical properties, which make them different from the bulk material. These properties of nanomaterials help them to find a variety of applications in the biomedical, agricultural, and environmental domains. Cerium oxide nanoparticles have gained a lot of attention as a potential future candidate for ending various kinds of problems by exhibiting redox activity, free radical scavenging property, biofilm inhibition, etc. Synthesis of these nanoparticles can be performed very easily by utilizing chemical or biological methods. But in this review, the focus is laid on the biosynthesis of these nanoparticles; as the biosynthesis method makes the cerium oxide nanoparticle less toxic and compatible with the living tissues, which helps them to find their path as an anticancer, anti-inflammatory and antibacterial agents. The pre-existing reviews have only focused on details relating to properties/applications/synthesis; whereas this review draws attention towards all the aspects in single review covering all the details in depth such as biosynthesis methods and its effect on the living tissues, along with properties, biomedical applications (diagnostic and therapeutic) and future outlook of the cerium oxide nanoparticle.

/pdf/cerium-oxide-nanoparticles-properties-biosynthesis-and-497m7ar942.pdf

Cerium oxide nanoparticles: properties, biosynthesis and biomedical application

Metal oxide nanomaterials are one of the preferences as antibacterial active materials. Due to its distinctive electronic configuration and suitable properties, ZnO is one of the novel antibacterial active materials. Nowadays, researchers are making a serious effort to improve the antibacterial activities of ZnO by forming a composite with the same/different bandgap semiconductor materials and doping of ions. Applying capping agents such as polymers and plant extract that control the morphology and size of the nanomaterials and optimizing different conditions also enhance the antibacterial activity. Forming a nanocomposite and doping reduces the electron/hole recombination, increases the surface area to volume ratio, and also improves the stability towards dissolution and corrosion. The release of antimicrobial ions, electrostatic interaction, reactive oxygen species (ROS) generations are the crucial antibacterial activity mechanism. This review also presents a detailed discussion of the antibacterial activity improvement of ZnO by forming a composite, doping, and optimizing different conditions. The morphological analysis using scanning electron microscopy, field emission-scanning electron microscopy, field-emission transmission electron microscopy, fluorescence microscopy, and confocal microscopy can confirm the antibacterial activity and also supports for developing a satisfactory mechanism. Graphical abstract showing the metal oxides antibacterial mechanism and the fluorescence and scanning electron microscopic images.

/pdf/a-review-on-enhancing-the-antibacterial-activity-of-zno-ej22bil2ly.pdf

A Review on Enhancing the Antibacterial Activity of ZnO: Mechanisms and Microscopic Investigation

The use of metal oxide nanoparticles is one of the promising ways for overcoming antibiotic resistance in bacteria. Iron oxide nanoparticles (IONPs) have found wide applications in different fields of biomedicine. Several studies have suggested using the antimicrobial potential of IONPs. Iron is one of the key microelements and plays an important role in the function of living systems of different hierarchies. Iron abundance and its physiological functions bring into question the ability of iron compounds at the same concentrations, on the one hand, to inhibit the microbial growth and, on the other hand, to positively affect mammalian cells. At present, multiple studies have been published that show the antimicrobial effect of IONPs against Gram-negative and Gram-positive bacteria and fungi. Several studies have established that IONPs have a low toxicity to eukaryotic cells. It gives hope that IONPs can be considered potential antimicrobial agents of the new generation that combine antimicrobial action and high biocompatibility with the human body. This review is intended to inform readers about the available data on the antimicrobial properties of IONPs, a range of susceptible bacteria, mechanisms of the antibacterial action, dependence of the antibacterial action of IONPs on the method for synthesis, and the biocompatibility of IONPs with eukaryotic cells and tissues.

https://www.mdpi.com/2079-6382/10/7/884/pdf

Do Iron Oxide Nanoparticles Have Significant Antibacterial Properties

Nanoceria has recently received much attention, because of its widespread biomedical applications, including antibacterial, antioxidant and anticancer activity, drug/gene delivery systems, anti-diabetic property, and tissue engineering. Nanoceria exhibits excellent antibacterial activity against both Gram-positive and Gram-negative bacteria via the generation of reactive oxygen species (ROS). In healthy cells, it acts as an antioxidant by scavenging ROS (at physiological pH). Thus, it protects them, while in cancer cells (under low pH environment) it acts as pro-oxidant by generating ROS and kills them. Nanoceria has also been effectively used as a carrier for targeted drug and gene delivery in vitro and in vivo models. Besides, nanoceria can also act as an antidiabetic agent and confer protection towards diabetes-associated organ pathophysiology via decreasing the ROS level in diabetic subjects. Nanoceria also possesses excellent potential in the field of tissue engineering. In this review, firstly, we have discussed the different methods used for the synthesis of nanoceria as these are very important to control the size, shape and Ce3+/Ce4+ ratio of the particles upon which the physical, chemical, and biological properties depend. Secondly, we have extensively reviewed the different biomedical applications of nanoceria with probable mechanisms based on the literature reports. The outcome of this review will improve the understanding about the different synthetic procedures and biomedical applications of nanoceria, which should, in turn, lead to the design of novel clinical interventions associated with various health disorders.

/pdf/synthesis-and-biomedical-applications-of-nanoceria-a-redox-2oq7jobifu.pdf

Synthesis and biomedical applications of nanoceria, a redox active nanoparticle

Cancer immunotherapy has emerged as a promising strategy for the treatment of many forms of cancer by stimulating body's own immune system. This therapy not only eradicates tumor cells by inducing strong anti-tumor immune response but also prevent their recurrence. The clinical cancer immunotherapy faces some insurmountable challenges including high immune-mediated toxicity, lack of effective and targeted delivery of cancer antigens to immune cells and off-target side effects. However, nanotechnology offers some solutions to overcome those limitations, and thus can potentiate the efficacy of immunotherapy. This review focuses on the advancement of nanoparticle-mediated delivery of immunostimulating agents for efficient cancer immunotherapy. Here we have outlined the use of the immunostimulatory nanoparticles as a smart carrier for effective delivery of cancer antigens and adjuvants, type of interactions between nanoparticles and the antigen/adjuvant as well as the factors controlling the interaction between nanoparticles and the receptors on antigen presenting cells. Besides, the role of nanoparticles in targeting/activating immune cells and modulating the immunosuppressive tumor microenvironment has also been discussed extensively. Finally, we have summarized some theranostic applications of the immunomodulatory nanomaterials in treating cancers based on the earlier published reports.

/pdf/nanoparticles-as-smart-carriers-for-enhanced-cancer-50uffi9g8x.pdf

Neelam Thakur

Papers

Synthesis and biomedical applications of nanoceria, a redox active nanoparticle

Nanoparticles as Smart Carriers for Enhanced Cancer Immunotherapy.